The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree ...The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree of damage is different, were selected from Tongchun, Qilin, and Pingdingshan mines. Using a series of experiments in an electrostatic field, we analyzed the characteristics of gas adsorption and diffusion in tectonic coal. We found that gas adsorption in coal conforms to the Langmuir equation in an electrostatic field. Both the depth of the adsorption potential well and the coal molecular electronegativity increases under the action of an electrostatic field. A Joule heating effect was caused by changing the coal–gas system conductivity in an electrostatic field. The quantity of gas adsorbed and DP result from competition between the depth of the adsorption potential well, the coal molecular electronegativity, and the Joule heating effect. DP peaks when the three factors control behavior equally. Compared with anthracite, the impact of the electrostatic field on the gas diffusion capacity of middle and high rank coals is greater. Compared with the original coal, the gas adsorption quantity, DP, and the gas diffusion capacity of tectonic coal are greater in an electrostatic field. In addition, the smaller the particle size of tectonic coal, the larger the DP.展开更多
为实现沁南地区煤层气井高产稳产,以沁南地区无烟煤为研究对象,采集不同煤矿3^(#)煤层的5个煤样,采用低温液氮吸附实验并结合扫描电子显微镜(scanning electron microscope,SEM)研究煤储层孔隙结构特征。结果表明:变质孔和溶蚀孔在沁南...为实现沁南地区煤层气井高产稳产,以沁南地区无烟煤为研究对象,采集不同煤矿3^(#)煤层的5个煤样,采用低温液氮吸附实验并结合扫描电子显微镜(scanning electron microscope,SEM)研究煤储层孔隙结构特征。结果表明:变质孔和溶蚀孔在沁南无烟煤中尤为常见,可见较多微裂隙,张裂隙和剪裂隙均有发育;孔隙以微孔为主,大多为吸附孔,渗流能力较差,平均比表面积为1.34185 m^(2)/g,平均孔容为0.00720 cm^(3)/g,平均孔径为29.24 nm;低温液氮吸附回线可以划分为3种类型,HX1型和HX2型孔隙形态以狭窄缝隙形孔为主,但HX2型存在部分两端开口透气性孔和少量墨水瓶形孔;HX3型孔隙形态由2个部分组成,在孔径<4.5 nm范围主要为狭窄缝隙形孔,在孔径>4.5 nm范围主要为狭窄缝隙形孔和墨水瓶形孔;以相对压力0.5为分界点,低压段和高压段具有不同的孔隙结构分形特征,分形维数D_(1)和D_(2)与吸附回线类型具有明显相关性。展开更多
基金the National Natural Science Foundation of China(No.41272177)the Henan Polytechnic University Doctor Foundation(No.WS2013A11)
文摘The characteristics of adsorption, desorption, and diffusion of gas in tectonic coal are important for the prediction of coal and gas outbursts. Three types of coal samples, of which both metamorphic grade and degree of damage is different, were selected from Tongchun, Qilin, and Pingdingshan mines. Using a series of experiments in an electrostatic field, we analyzed the characteristics of gas adsorption and diffusion in tectonic coal. We found that gas adsorption in coal conforms to the Langmuir equation in an electrostatic field. Both the depth of the adsorption potential well and the coal molecular electronegativity increases under the action of an electrostatic field. A Joule heating effect was caused by changing the coal–gas system conductivity in an electrostatic field. The quantity of gas adsorbed and DP result from competition between the depth of the adsorption potential well, the coal molecular electronegativity, and the Joule heating effect. DP peaks when the three factors control behavior equally. Compared with anthracite, the impact of the electrostatic field on the gas diffusion capacity of middle and high rank coals is greater. Compared with the original coal, the gas adsorption quantity, DP, and the gas diffusion capacity of tectonic coal are greater in an electrostatic field. In addition, the smaller the particle size of tectonic coal, the larger the DP.
